I will attend the Okie-Tex Star Party in late September. I will be taking my 6” Schmidt-Newtonian (guided on a G8) equipped with an ATIK 314L+ and BVI filters. So it’s several nights (weather permitting) of opportunity. My initial though was to pick some eclipsing binaries from the EB program, and I have done so. I have done EBs before, so I am familiar with this program. But, I thought I might throw this out to more experienced observers.
Any other projects that might benefit from more-more-less continuous multi-night/all-night time series data collecting for a 6”F4 scope? If there is something interesting I will need some lead time to insure I have a chance for success by figuring the imaging parameters for the potential FOVs.
Motivation: set it up and then have fun doing visual observing while monitoring the observing run on the 6".
Thanks for any suggestions,
Ed
Hi Ed,
With the 6-inch, you should be able to do ~12th magnitude at V in one minute with signal/noise of 100. That only gives you 2 million stars to choose from. :-)
That time of year is good for Cygnus and Cassiopeia. I like QX Cas, up near NGC 7790. It is a 10th magnitude blue binary. In the 1960's, it had a 0.5mag eclipse, but there is a third body in the system and for several decades, no hint of an eclipse has been present. However, I'd like to get a good light curve about once/year to keep an eye on the system - if the eclipses went away, then they should be back some day! That would be a simple target to do. With enough field to cover NGC7790, you also pick up several other variables for free, such as the cepheid variable CF Cas, so even if QX Cas is constant, you have plenty of other things to analyze.
Arne
Hi Arne:
A bit more direction for me would help. Should I simply sit on QX Cas each night taking, say, 25 images/hour? Objective would be to catch an eclipse sometime during the 7 or so days of observation? If so, it sounds like a simple project indeed. VSX yields a period of 6.00471 days, so I am assuming that 7 days of coverage would do. I can practive on it now and get my FOV and integration times down, plenty of time. I'll bring my 1T harddrive and I can reduce each night's data the next day.
Let me know if this sounds reasonable and many thanks for the suggestion.
Ed
QX Cas has a 6-day period; the NGC7790 cepheids are around 5 days; there are some delta scuti stars in the cluster with periods of a few hours. So any cadence works. If you picked a cadence that was optimal for the binary, then the usual rule of thumb is about 100 points per cycle, or an observation every 1.4 hours - that is, you don't have to sit on the field. However, it sounded like you wanted to set your telescope up and leave it alone, in which case a higher cadence won't hurt (and resolves other variables in the same field).
The problem with a 6d period is that it is impossible to see the daylight half of the light curve. You have to wait until the 0.00471d builds up to 0.471 days, or about 100 cycles (600 days). So you can cover one half of the light curve really good this year, and then wait until next year to cover the other half (or find a friend in China to get the other half of the light curve now!). So it is a good background project - get 6 night's worth of photometry and call it good for the year.
Yes, the objective is to catch an eclipse. If the eclipse "season" is just starting, the depth may be very shallow, so high precision is the rule - which is one reason why you might want higher cadence and then average several datasets together.
Arne
Thanks Arne:
This sounds like a good project. May I contact you via email for some other details of the project?
Ed
Hi Ed,
sure, I'm always available via email when needed.
Arne
A integrated campaign with several observers working in "tandem" in diferent time zones would render a good result.
making the probability of geting the eclipse. and producing a full light curve
Best regards
JAC
I agree, but I am too much of a novice to organize such a thing. I just checked the ephemeris in SkyTools3; a minimum is predicted on 20 September, the first night of my planned series of observations. I have no idea if these are good data or not. Apparently the eclipse lasts about 13 hours.
Ed
Ed, VSX has emphemerides for all periodic stars for a few cycles into the future; just click on the link to the right of the "epoch" parameter. However, for your case, the VSX emphemeris ends on 9 Sept, so using SkyTools3 was appropriate.
For objects like QX Cas, where an eclipse has not been seen in 50 years, don't trust any ephemeris. However, for most binary stars, a good rule of thumb is that the eclipse takes about 1/10 of the period; your 13 hours matches the 0.6days from that guideline, and so it would only take one more observer and 6 consecutive clear nights to cover enough of the cycle to rule out any eclipse.
Arne
Ed, Arne and others as well. I have here observations of NGC 7790 in BVRI since the beginning of 2000-s, made not exactly every night but still quite often to create transformations. My location is 26degrees east, so while I'm still far from China, the location is still much more eastwards compared to east coast of US ;-) If there should be interest in them, I could process them relatively easily and submit data to AAVSO database.
Best wishes,
Tõnis
Hi Tõnis:
I am too much of a beginner to know. Perhaps Arne will respond. Better yet, perhaps you could send him an email.
Ed